Cross-platform compatibility will allow for 2 different features: cross-play and cross-save.

Cross-play enables you to play against players on other platforms; for example, allowing you to match against console players while playing on your phone.

Cross-play will be enabled across all platforms.

Cross-save allows you to transfer your game progress to a different device; for example, transferring your account progress on your iPhone to be able to continue playing on a PC.